As a kind of system which estimates a value which is impossible to be measured physically based on a feature extracted from inputted information, there is a system that estimates the age and the gender of a person by extracting a feature of the person from inputted image data and comparing the extracted feature with data learned in advance.
For example, as shown in FIG. 1, a system having feature extraction units to extract a feature from an input image and a classifier which estimate an age by comparing the extracted feature with data learned in advance is related.
In the above-mentioned related system, as a classifier which processes an extracted feature to estimate an age, there is a case where an estimated result is handled as a discrete quantity like invention disclosed in patent document 1 and a case where it is handled as a continuous quantity like invention disclosed in patent document 2.    [Patent document 1] Japanese Patent Application Laid-Open No. 2007-58828    [Patent document 2] Japanese Patent Application Laid-Open No. 2005-148880